Wednesday 3^rd February comments: The Isle of May supports an array of seabirds from the cliffnesters to the ground nesting species. All have different characteristics and different breeding strategies but importantly all use the Isle of May as an important breeding ground, which offers protection, good place to nest with plentiful food supply to raise young. Today we look at a species which is currently not in U’K. waters as we say hello to the Sandwich Tern.  

Description

Sandwich Terns are the largest of all the British breeding terns and can be distinguished by their larger size, long black bill with yellow tip, crested shaggy crown and black legs. Interestingly it gets its name from the historic town in Kent where it was first described to science. The species is often very vocal, with a loud ‘kear-ik’ or ‘kerr ink’ call. The species is 37–43cm (15–17 inches) long with an 85–97cm (33–38 inches) wingspan and can weigh between 180-300g. Like the majority of tern species, it plunge dives for prey off the surface of the sea.

Breeding Biology

Unlike many other tern species, Sandwich Terns show little territoriality crowding as they nest together to breed often within other tern colonies which provide protection from predators. On the Isle of May they nest closely with Common and Arctic Terns and normally lay 1-2 eggs. Sandwich terns display little pre-breeding attendance unlike many other seabirds, laying 2-3 days after arriving already paired in many cases. The late arrival on the breeding grounds usually mid -may on the Isle of May) acts as an additional predator defence, since by cutting down the time spent at the colony they reduce the time that they are exposed to predators.

Both sexes will incubate and care for the young and after fourteen days after hatching, chicks can form large crèches, chaperoned by a few adults (usually 1 adult to 10 chicks). Sandwich Terns feed on a variety of prey but mainly on small marine fish, typically sand eels, clupeids (Herring) and sprats. After the breeding season, birds move off to the nearby coast before heading south and we’ll reveal more on their winter movements in tomorrows blog…